The objectives of this project are threefold. The first objective is to examine selected chemicals employing a defined panel of assays, for their ability to induce immunosuppression, hypersensitivity or autoimmune disease in the rodents. A second objective is to develop and establish methodology with predictive value in determining potentially immunotoxic chemicals. Finally, this project will examine the cellular and molecular events associated with immunotoxicity. To obtain the most accurate estimate possible of chemical safety, there is a need to increase the existing database regarding the potential for chemicals to affect the immune system, as well as to understand the basic cellular and molecular events underlying overt manifestations of immunotoxicity. in addition, there exists a large number of chemicals, including environmental agents and therapeutic drugs, which have not been examined for their effects on the immune system in animal models, and represent a potential threat to human health. This project will utilize a comprehensive immune assay panel to evaluate the immune system for both suppression and enhancement, as well as hypersensitivity. it will also involve the development and validation of assays to determine the potential of xenobiotics to induce autoimmunity.